“Building K-25 represents the largest demolition project ongoing in the (U.S. Department of Energy’s) Environmental Management complex today,” according to UCOR’s release. “Work began in 2008 under a previous contractor and is expected to be complete sometime next year.”

The K-25 building, located at ETTP (formerly known as the Oak Ridge Gaseous Diffusion Plant), was composed of three major sections — the east and west wings and the north end — which were aligned in a “U” shape that was more than a mile around. The north end forms the base of the “U” and is the smallest of the three sections.

UCOR president & project manager Leo Sain said the K-25 building was the largest building constructed in World War II as part the nation’s top-secret “Manhattan Project.”

He said the K-25 building measured 400 feet wide, 65 feet high and a half-mile long in sections.

“It was 44 acres under roof,” Sain noted during Wednesday morning’s ceremony, pointing out that the next largest building was the K-33 building, which was 32 acres under roof.

UCOR reports that demolition of the north, west and east wings is now complete … with the exception of a small section of the east wing that requires further deactivation due to the presence of technetium-99. Tc-99 is a slow-decaying radioactive metal.

“Previous plans called for the north end to be preserved for historic purposes,” UCOR stated in Wednesday’s release. “But, in July 2012, federal, state and local historic preservation groups signed an agreement establishing an alternative plan that allows the north end to be demolished, while still recognizing the historic significance of the site.”

Regarding the demolition milestone celebrated this week, K-25 D&D manager Mark Ferri remarked that “the employees here at K-25 have made this happen.

“I have been impressed with their knowledge and absolute focus on safety since Day One. They are the best group I have ever been privileged to work with.”

Within weeks after UCOR took over the ETTP contract in August 2011, workers began work on the east wing and soon completely cut through the wing, allowing demolition work to be safely conducted in the “non-Tc area” at the same time that deactivation work was being done in the technetium-99 area.

Waste disposition work has kept pace with demolition work under the project’s “pack as you go” philosophy. This means waste isn’t allowed to pile up in the wake of demolition; instead, waste is shipped within weeks after demolition is completed.

In all, workers have safely completed more than 15,000 shipments since the contract began, UCOR stated.

Workers are now expected to continue pre-demolition activities in the remaining Tc-99 area of K-25’s east wing. And, depending on funding, the last section of K-25 could be completed some time next year.

“Completing demolition of the K-25 building is our highest priority, and this is another significant step toward that goal,” said Mark Whitney, Oak Ridge’s EM manager.

In addition to deactivating and demolishing K-25 and other clean-up work, UCOR is responsible for other specific scopes of work at ETTP, the Y-12 National Security Complex, and the Oak Ridge National Laboratory.